CN111925640A

CN111925640A - Anti-bending polycarbonate composite material for injection molding and preparation and application thereof

Info

Publication number: CN111925640A
Application number: CN202010818184.8A
Authority: CN
Inventors: 李东阵; 袁会宁
Original assignee: Guangzhou Chendong New Materials Co ltd
Current assignee: Guangzhou Chendong New Materials Co ltd
Priority date: 2020-08-14
Filing date: 2020-08-14
Publication date: 2020-11-13
Anticipated expiration: 2040-08-14
Also published as: CN111925640B

Abstract

The invention belongs to the field of composite materials, and discloses an anti-bending polycarbonate composite material for injection molding and preparation and application thereof. The composite material comprises the following components in percentage by weight: 90% -98% of polycarbonate resin; 0.5 to 5 percent of glass powder; 0.5 to 5 percent of hydrocarbon; 0.05 to 0.5 percent of antioxidant; 0.1 to 2.0 percent of release agent. According to the invention, by adding the glass powder and the hydrocarbon, the chemical resistance of the welding line part of the workpiece can be greatly improved, the bending resistance of the product after the spraying process is greatly improved, the cracking is reduced, and the yield is improved. In addition, cross-linked PC or copolymerized silicon PC can be added into the composite material, when the cross-linked PC or copolymerized silicon PC is combined with glass powder/polyethylene for use, the bending performance of the material is further improved, and when the proper combination is used, the bending performance after spraying can reach the same level as that before PC spraying.

Description

Anti-bending polycarbonate composite material for injection molding and preparation and application thereof

Technical Field

The invention belongs to the field of composite materials, and particularly relates to an anti-bending polycarbonate composite material for injection molding and preparation and application thereof.

Background

Polycarbonate (PC) is widely used as a mobile phone rear shell material due to good impact resistance, and has the advantages of portability, drop resistance, good dielectric property and the like. With the popularization of large screens, the difference of the front of the mobile phone is smaller and smaller, and in order to meet the requirements of individuation and differentiation, mobile phone manufacturers can only make articles on the rear shell, so that various appearance effects are realized. In order to achieve various appearance effects, PC is often required to be painted and surface treated. Due to poor resistance of PC, various chemical agents used in spraying and surface treatment have a significant effect on PC, resulting in a decrease in toughness of PC, direct cracking, or bending cracking. Such cracking tends to occur near the weld line, mainly for two reasons, one being that the weld line itself is weaker than elsewhere and has poor toughness. And secondly, the part near the welding line is always provided with stronger residual stress and is more easily attacked by chemical reagents. Particularly, as the weight of the 5G mobile phone increases and the appearance is extremely desired, a stronger chemical agent is required for surface treatment. The PC material suitable for use in the past has high reject ratio under the new requirements of toughness and bending, and the requirements are difficult to meet.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention mainly aims to provide the bending-resistant polycarbonate composite material for injection molding, which is added with glass powder and hydrocarbon, so that the chemical resistance of a welding line part of a workpiece can be greatly improved, the bending resistance of the product after a spraying process is greatly improved, cracking is reduced, and the yield is improved.

The invention also aims to provide a preparation method of the bending-resistant polycarbonate composite material for injection molding.

The invention further aims to provide application of the bending-resistant polycarbonate composite material for injection molding.

The purpose of the invention is realized by the following scheme:

a bending-resistant polycarbonate composite material for injection molding comprises the following components in percentage by weight:

the glass powder is preferably surface modified glass powder, wherein the surface modified compound is polyolefin, and is preferably Chongqing International 415A-14C; the D50 of the glass powder is less than 5 um; preferably less than 2 um;

the weight percentage of the glass powder is preferably 1-3%;

the hydrocarbon is polyethylene with the number average molecular weight of 1000-.

The weight percentage of the hydrocarbon compound is preferably 1 to 5%, more preferably 1 to 2%.

The antioxidant is hindered phenol antioxidant or phosphite antioxidant, and the release agent is stearate.

Further, the bending-resistant polycarbonate composite material for injection molding comprises the following components in percentage by weight:

further, the bending-resistant polycarbonate composite material for injection molding can also comprise polycarbonate (water barrel PC or cross-linked PC) with a cross-linked structure, namely the polycarbonate resin is a blend of the polycarbonate (water barrel PC or cross-linked PC) with the cross-linked structure and common non-cross-linked polycarbonate, and the bending-resistant polycarbonate composite material comprises the following components in percentage by weight:

wherein the weight percentage of crosslinked PC is preferably 20-30%;

further, the bending-resistant polycarbonate composite material for injection molding can also comprise polysiloxane-polycarbonate copolymer, and the bending-resistant polycarbonate composite material comprises the following components in percentage by weight:

wherein the weight percent of polysiloxane-polycarbonate copolymer is preferably 20-30%;

the preparation method of the bending-resistant polycarbonate composite material for injection molding comprises the following steps: the components are mixed according to the proportion and then extruded and granulated by an extruder to obtain the bending-resistant polycarbonate composite material for injection molding, wherein the granulation temperature is 230-300 ℃.

The bending-resistant polycarbonate composite material for injection molding is applied to preparation of a mobile phone rear shell.

Compared with the prior art, the invention has the following advantages and beneficial effects:

the polycarbonate composite material for injection molding can greatly improve the chemical resistance of the welding line part of a workpiece, greatly improve the bending resistance of the product after a spraying process, reduce cracking and improve the yield. The preparation method is simple and feasible, and is suitable for large-scale production and application.

Drawings

FIG. 1 is an illustration of the bend cracking of the reference 1 article after the spray coating process of example 1.

Detailed Description

The present invention will be described in further detail with reference to examples and drawings, but the embodiments of the present invention are not limited thereto. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially. The glass powder is prepared by grinding PC (polycarbonate) serving as Taihua light TARFLON IR1900, cross-linked PC serving as LG LUPOY 1603, copolymerized silicon PC serving as Xintong color D0013, glass powder 1, 2 and 3 by Chongqing International 415A-14C, glass powder 4 by Chongqing International 303H-3 and glass powder 5 by Chongqing International 301 HP-3.

Example 1

The components in table 1 were mixed in a mixer in the weight ratios shown in table 1, and then pelletized with a twin-screw extruder at a temperature of 240 ℃ to 280 ℃. The obtained particles are injected on a real mobile phone mold, a sample after injection molding is divided into two parts, and one part is directly subjected to bending test (the test mode is that a workpiece is bent in the same direction by taking the central line of the long edge as a symmetry axis, and the bending angle when fracture occurs is recorded). The other part was subjected to spray test. The spraying test is that the Taiwan blue brand HD-130 spray gun is used for spraying the Tiantong water on one side of the workpiece at the speed of 2.5cm/s and the distance between the nozzle of the spray gun and the surface of the workpiece is 2 cm. And (3) standing for 24 hours after spraying, observing whether the workpiece cracks, if not, carrying out bending test on the sprayed workpiece, and recording the bending angle when the workpiece cracks. When bending test is carried out, 3 samples are tested for each sample, and an average value is taken. The test results are shown in table 1.

TABLE 1 comparative test data for different glass powders

The parameters of the glass frit in table 1 are shown in table 2, and the parameters of the polyethylene are shown in table 3.

TABLE 2 glass powder parameter table

	Glass powder 1	Glass powder 2	Glass powder 3	Glass powder 4	Glass powder 5
						Surface treatment	Polyolefins	Polyolefins	Polyolefins	Siloxanes	Amino silane
D50	1.2um	3um	10um	3um	3um

TABLE 3 polyethylene parameter Table

	Polyethylene 1	Polyethylene 2	Polyethylene 3
				Molecular weight	800	2000	>10000

From the data in table 1, it can be seen that even pure PC has very good bending properties when no spraying is performed. However, when the parts are sprayed, pure PC is directly broken at the weld line. When the glass powder was added, the impact strength and bending resistance of PC further declined even with the addition of a small amount of glass powder having a small particle size (sample 1). When a small amount of polyethylene was added (sample 2), the performance of the system did not change significantly. When small-particle-size glass powder and a small amount of polyethylene are added simultaneously, the impact strength and the bending resistance of PC are improved to different degrees. Particularly, the paint can not be directly broken after being sprayed, and has a certain bending resistance angle. This is probably due to the strong affinity of the polyolefin to the glass frit, which aids in the dispersion of the glass frit at the weld line. Meanwhile, as the hardness of the glass powder is obviously higher than that of PC, according to the toughening theory, the fine hard particles can help the system to absorb energy and improve the toughness of the system.

Meanwhile, the glass powder with different surface treatments has different effects, and the polyolefin surface modified glass powder has better performance than the siloxane and aminosilane modified glass powder, which is probably also the reason that the polyolefin surface modified glass powder has better affinity with polyethylene and is easier to disperse. In addition, when the glass frit has a larger particle size or a higher polyethylene content, the system performance and bending resistance are significantly reduced, which should be because the large particles of glass frit and the large amount of polyethylene more reduce the toughness of the system in the form of defects.

Example 2

The components in table 4 were mixed in a mixer in the weight ratios shown in table 4, and then pelletized with a twin-screw extruder at a temperature of 240 ℃ to 280 ℃. The obtained particles are injected on a real mobile phone mold, a sample after injection molding is divided into two parts, one part is directly subjected to bending test (the test mode is that a workpiece is bent in the same direction by taking the central line of the long edge as a symmetry axis, and the bending angle when fracture occurs is recorded), and the bending angle when fracture occurs is recorded. And spraying the other part of the mixture by using a Taiwan blue brand HD-130 spray gun to spray the Tiantashui on one surface of the workpiece at the spraying speed of 2.5cm/s, wherein the distance between the nozzle of the spray gun and the surface of the workpiece is 2 cm. And (3) standing for 24 hours after spraying, observing whether the workpiece cracks, if not, carrying out bending test on the sprayed workpiece, and recording the bending angle when the workpiece cracks. When bending test is carried out, 3 samples are tested for each sample, and an average value is taken. The test results are shown in table 4.

TABLE 4 influence of different polyethylenes on the data Performance

As can be seen from the data in table 4, the molecular weight of the polyethylene has a significant effect on the bending resistance of the material, with polyethylene having a molecular weight of 2000 showing the best bending resistance. This is probably because it is difficult to effectively disperse the glass powder both when the molecular weight is too small and when the molecular weight is too large.

Example 3

The components in table 5 were mixed in a mixer in the weight ratios shown in table 5, and then pelletized with a twin-screw extruder at a temperature of 240 ℃ to 280 ℃. The obtained particles are injected on a real mobile phone mold, a sample after injection molding is divided into two parts, one part is directly subjected to bending test (the test mode is that a workpiece is bent in the same direction by taking the central line of the long edge as a symmetry axis, and the bending angle when fracture occurs is recorded), and the bending angle when fracture occurs is recorded. The other part was subjected to spray test. And in the spraying test, spray the Tianpan water on one surface of the workpiece by using a spray gun, standing for 24 hours after spraying, observing whether the workpiece cracks, if not, carrying out bending test on the sprayed workpiece, and recording the bending angle when the workpiece cracks. When bending test is carried out, 3 samples are tested for each sample, and an average value is taken. The test results are shown in table 5.

TABLE 5 influence of Cross-linking PC and copolysilicon PC on bending Properties

It can be seen from the data in table 5 that when cross-linked PC or copolypc PC is used in combination with glass frit/polyethylene, the bending properties of the material are further improved and when the appropriate combination is used, the bending properties after spraying can reach the same level as before PC spraying. And the effect of the combination is better than that of singly using the cross-linked PC, singly using the copolymerized PC or singly using the glass powder/polyethylene. Initially, as the content of cross-linked PC and copolymerized silicon PC increases, the bending resistance increases. However, when the content of the crosslinked PC and the copolymerized PC is too high, although the impact resistance continues to be improved, the bending resistance starts to be lowered, which is probably due to the poor flowability of the crosslinked PC and the silicon copolymerized PC, which affects the strength of the weld line portion.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.

Claims

1. The bending-resistant polycarbonate composite material for injection molding is characterized by comprising the following components in percentage by weight:

2. the bend-resistant polycarbonate composite for injection molding according to claim 1, wherein:

the glass powder is surface modified glass powder, wherein the surface modified compound is polyolefin; the D50 of the glass powder is less than 5 um.

3. The bend-resistant polycarbonate composite for injection molding according to claim 1, wherein:

4. The bend-resistant polycarbonate composite for injection molding according to claim 1, wherein:

the glass powder is Chongqing International 415A-14C; the D50 of the glass powder is less than 2 um;

the hydrocarbon is polyethylene with the number average molecular weight of 2000;

the weight percentage of the glass powder is 1-3%.

5. The bend-resistant polycarbonate composite for injection molding according to claim 1, wherein:

6. The bend-resistant polycarbonate composite material for injection molding according to claim 1, characterized by comprising the following components in percentage by weight:

7. the bend-resistant polycarbonate composite material for injection molding according to any one of claims 1 to 6, wherein:

the bending-resistant polycarbonate composite material for injection molding further comprises polycarbonate with a cross-linked structure, namely cross-linked PC for short, namely the polycarbonate resin as a main material is a mixture of the cross-linked PC and non-cross-linked polycarbonate resin, and the bending-resistant polycarbonate composite material for injection molding comprises the following components in percentage by weight:

8. the bend-resistant polycarbonate composite material for injection molding according to any one of claims 1 to 6, wherein:

the bending-resistant polycarbonate composite material for injection molding further comprises polysiloxane-polycarbonate copolymer, and the bending-resistant polycarbonate composite material for injection molding comprises the following components in percentage by weight:

9. a preparation method of the bend-resistant polycarbonate composite material for injection molding according to any one of claims 1 to 8, characterized by comprising the following steps: the components are mixed according to the proportion and then extruded and granulated by an extruder to obtain the bending-resistant polycarbonate composite material for injection molding, wherein the granulation temperature is 230-300 ℃.

10. Use of the bend-resistant polycarbonate composite material for injection molding according to any one of claims 1 to 8 in the preparation of a mobile phone rear shell.